18 Questions
What type of evidence is sufficient to demonstrate that competition is occurring in the wild?
Experimental manipulations
Which of the following evidences is NOT sufficient to demonstrate competition in the wild?
Correlations in abundance
According to Gause’s competitive exclusion principle, what does character displacement suggest?
Evolutionary adaptation to avoid competition
When studying competition, what might evolution of traits like character displacement indicate about species?
Resource partitioning to reduce competition
In the context of competition, what do isoclines represent in a phase plane diagram?
Population equilibrium points
How do terns, Sooty and Brown Noddy, exhibit character displacement in their feeding behavior?
Sooty feeds far at sea, Brown Noddy feeds near shore
Which type of evidence is considered the best for demonstrating competition in the wild?
Experimental manipulations of competitor densities
What is the relationship between competitors at some spatial scales according to the passage?
Competitors can be positively correlated at some scales and negatively correlated at others
In the example experiment described, what was the purpose of growing the red fish and blue fish in different starting combinations?
To determine the competitive interactions between the red and blue fish
According to the passage, which of the following is an example of a non-transitive relationship between competitor types?
Yellow beats blue, blue beats orange, and orange beats yellow
Which of the following factors could potentially cause a negative correlation in abundance between possible competitors?
Predation or other external biotic interactions
How do the non-transitive relationships between competitor types mentioned in the passage allow them to coexist?
By preventing any single type from competitively excluding the others and dominating the community
What was the purpose of the competition experiments described in the text?
To test the effect of competition on the distribution of barnacle species in the subtidal zone
Based on the results presented, what can be concluded about the effect of competition between Chthamalus and Balanus?
Competition limited the lower end of the Chthamalus distribution but not the upper end of the Balanus distribution
How do the Lotka-Volterra competition model equations presented in the text relate to the experimental results?
The equations can be used to make predictions about the outcome of competition between the two species
What is the significance of the "isoclines" mentioned in the text?
They are used to visualize the dynamics of the Lotka-Volterra competition model
How do the results of the competition experiments relate to the evolution of traits in the two barnacle species?
The results suggest that competition has led to character displacement in the two species
What is the relationship between the abundance of Chthamalus and Balanus based on the information provided in the text?
The abundance of the two species is negatively correlated, with Chthamalus being more abundant in the high zone and Balanus being more abundant in the low zone
Study Notes
Phase Plane Analysis
- Initial and final abundances of blue and red fish are used to draw isoclines in a phase plane.
- The number of blue fish (NB) and red fish (NR) are plotted on the axes, with the carrying capacities (KB and KR) marked on the outside.
Evidence of Competition
- Observation of interactions is insufficient evidence of competition.
- Correlations in abundance can be misleading due to other factors like predation.
- Experimental manipulations are the most convincing evidence of competition.
- Evolution of traits, such as character displacement, can also be evidence of competition.
Character Displacement
- Character displacement occurs when different species develop distinct traits to coexist.
- This can be seen in morphological or behavioral differences, such as diet or feeding location.
- Example: Sooty and Brown Noddy terns have similar diets but feed at different distances from shore.
Non-Transitive Relationships
- Yellow, Blue, and Orange lizard types have non-transitive relationships, allowing them to coexist.
- Each type is a competitor, but they can be positively correlated at some spatial scales and negatively correlated at others.
Experimental Manipulations
- Experiments can be used to demonstrate competition, such as growing red and blue fish in different starting combinations.
- Example: An experiment showing competition in barnacle distribution in the subtidal zone.
Lotka-Volterra Models
- Interaction competition models can be used to predict the outcome of competition between two species.
- The equations describe the change in population size over time, taking into account the carrying capacities and competition coefficients.
- The phase space isoclines can be used to make predictions about who wins and whether coexistence is possible.
This quiz covers drawing isoclines, labeling axes and points on a phase plane diagram, and determining evidence of competition between species based on their population dynamics. Test your knowledge on these concepts with this quiz.
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